Effect of vacancies on blue-colored calcium phosphate scaffolds derived from Nile tilapia bone powder

This study explores the fabrication and characterization of porous ceramic scaffolds using the polyurethane sponge replication technique with commercial hydroxyapatite (SA-P) and Nile Tilapia bone-derived (FB-P) powders. Scaffolds sintered at 1300 °C and 1400 °C for 5 h exhibited high porosity (70-90%) with interconnected pores. SA scaffolds exhibited greater shrinkage due to differences in particle size and morphology. FTIR and XRD analyses confirmed hydroxyapatite (HAp), β-tricalcium phosphate (β-TCP), and α-tricalcium phosphate (α-TCP) phases, with compositions influenced by sintering temperature. FB scaffolds developed a distinct blue coloration attributed to hydroxyl (OH^-) and oxygen (O_v-PO₄) vacancies within the HAp, while SA scaffolds appeared lighter. UV-vis and XANES analyses validated these compositional differences. In vitro cytotoxicity assays confirmed the biocompatibility of all scaffolds, with SA scaffolds exhibiting higher cell viability and proliferation than FB scaffolds, likely due to their optimized microstructure and phase composition. While FB scaffolds showed slightly lower cell proliferation, their bioactivity remained sufficient for bone tissue engineering applications. These findings suggest a promising strategy for selectively enhancing the OH^- vacancy within the HAp structure and refining the HAp/β-TCP composition, thereby improving the biological performance of calcium phosphate scaffolds for biomedical applications.